This invention relates to a caliper brake for use in a bicycle or like vehicles.
Generally, a caliper brake is composed of first and second brake arms, a pivotal shaft for rotatably supporting the brake arms, a pair of brake shoes supported by the brake arms and a return spring. The first brake arm has a wire fixture mounted thereon which secures an end of an operating wire, while the second brake arm has an outer pipe support means mounted thereon which guides the operating wire. An operating lever, connected to another end of the operating wire, is provided on a handle bar, which, when operated, causes the brake arms to oscillate around a pivotal shaft bringing the brake shoes into contact against a wheel rim to brake the wheel.
When a bicycle is transported, the wheels are often disassembled from the bicycle frame, and later reassembled thereon. Old wheels may also be removed and replaced by new ones. In either case, the space between the brake shoes must be increased before the wheel can be removed or remounted.
In order to increase the distance between the brake shoes, one must loosen the operating wire extending between the brake arms and operating lever. For this purpose, a so-called quick-release mechanism is known in which the support means for an outer pipe guiding the operating wire is made movable with respect to the brake arm with the support means being moved by the lever.
With this mechanism, the support means for the outer pipe can be quickly moved through the operation of the lever to spread the space between the brake shoes. However, this system is of complex construction and is relatively expensive. It also suffers from the disadvantage that the pace between the brake shoes is not intended to spread to a maximum. Considering safety when the quick-releasing mechanism has failed, the space between the brake shoes is adapted to be spread to a lesser extent than the maximum possible. The limited spread between brake shoes achievable by this mechanism is particularly a problem with bicycles designed for racing across remote places among mountains, as they use thicker tires than those normally used in roadster, tourist, or sports type bicycles. The thicker tires cannot fit between the limited spread of the brake shoes and the wheels cannot be quickly released.
To accommodate the larger tires, the space between the brake shoes must be spread to a maximum. However, as described above, the conventional quick-releasing system is incapable of spreading the space between the brake shoes to a maximum. Accordingly, when large size tires are used for road racing, either the brake shoes must be removed or the operating wire must be removed from its fixture to replace the wheel.
This invention is designed to overcome the disadvantages described. Thus, an object of this invention is to provide a caliper brake wherein wheels mounted with normal tires and wheels for racing mounted with thicker tires can both be quickly and easily replaced. A further object of the invention is to provide a mechanism for spreading the space between the brake shoes which is inexpensive and which has component parts which cannot get lost.
These objects are accomplished by a brake shoe spreading mechanism comprising a shaft member which extends through a brake arm provided either on a fixture securing an end of an operating wire which is mounted on one of the brake arms or on a support means for an outer pipe guiding the operating wire which is mounted on the other brake arm. In either case, the shaft member is detachably mounted on its associated brake arm and projects through a bore therein with the projecting portion being provided with a groove. A retaining member, composed mainly of a wire material, is provided with a pivotal portion and an engaging portion. The pivotal portion is pivotally attached to the brake arm to which the shaft member is mounted to elastically engage the engaging portion with the groove. With this mechanism, even wheels mounting thicker tires can be quickly and easily replaced on the bicycle frame. Thus, a mechanism for spreading the space between the brake shoes can be formed inexpensively, and the parts can be prevented from being lost.
These and other objects and features of the invention will be apparent from the following detailed description which is taken in conjunction with the accompanying drawings.